ATCO ELECTRIC Micro-Generation Determination Application ... PROCEEDING 1477 -- ATCO... · Howell...

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ATCO Electric Micro-Generation Determination Application No. 1607742 Information Responses No. 1 to HME Date submitted: December 23, 2011

ATCO ELECTRIC Micro-Generation Determination

Application No. 1607742, Proceeding ID 1477

Information Responses No. 1 To: Howell Mayhew Engineering, Inc. (HME)

Received: December 2, 2011

HME-AE-1

Discussion #1: Definition of micro-generator as per Alberta Regulation 27/2008 1(1)(h)(ii): “is intended to meet all or a portion of the customer’s electricity needs”

Preamble: In its Notice of Dispute, the Owner used the phrases: “The proposed nominal generation capacity…”, “annual generation output”, “customer’s load”, “onsite load”, “the proposed generation”, “annual consumption”; and

in its Response, the Owner used the phrases: “electric power requirements”, “additional loading”, “customer’s load requirements”, “electric loads”, “area load”, “demand requirements”, “customer’s demand”, “operating demand”, “annual consumption patterns”, “lowest consumption”, “surplus generation”, “generation units”, “surplus capacity”.

Request:

Since the Owner has used the phrases above, which contain the electricity terms listed below, and since many people and organizations use such electricity terms to mean various different electricity parameters, is the Owner using each term to refer to an electrical energy flow (“Power”) (kW) parameter or using each term to refer to a total electrical energy (kWh) parameter, or using each term to refer to another electricity parameter? If the term is an electrical Power parameter, is the electrical Power referenced as at rated electrical conditions, or is it an instantaneous Power, average daily maximum Power, annual maximum Power, average annual Power or another Power level? If the term is an electrical energy parameter, is the electrical energy referenced over a day, month or year? If the term is another electricity parameter, what is this parameter, its measurement units and the range of its timeframe?

HME-AE-1 of 2


load demand electrical needs electric power requirements consumption generation capacity

Response:

Load and Demand – refers to the flow of real and reactive power, specifically to that consumed on the customer’s site. Depending upon the context, the reference could be to instantaneous flow or to the average flow over a period of time. In Paragraph 6 of ATCO Electric’s response, the term ‘loading’ is also used to refer to the flow of real and reactive power through the transformer.

Electric Power Requirements and Electrical Needs – refers to all aspects of the use of electricity by the customer, including power, energy, reliability, and the quality of the voltage and current waveforms.

Consumption - refers to the amount of energy required by the customer over a period of time.

Generation – refers to the power and energy produced by a generator.

Capacity – refers to the maximum amount of power that can be accommodated.

HME-AE-2 Page 1 of 1






HME-AE-2


Preamble: In its Notice of Dispute, the Owner stated: “The proposed nominal generation capacity is 20 kW…”.

Request:

Why is the Owner suggesting that 20 kW is the nominal generating capacity of the generating unit instead of the generating unit’s actual rated capacity of 17.3 kW?

Response:

As per the MG application submitted by HME, the Generator Rated Capacity was stated as 20.9 kW.







HME-AE-3


Preamble: In its Notice of dispute, the Owner stated: “ATCO Electric estimated annual generation output at 6 hr/day with 75% service factor equals 32,850 kWh annually”.

Request:

(a) What mathematically-validated industry-best-practice engineering documentation:

defines and explains the cited “6 hr/day” parameter;

explains and justifies the numerical value of “6 hr/day”; and

explains and justifies the application of “6 hr/day” to the Customer’s generating unit?

(b) What mathematically-valid industry-best-practice engineering documentation:

defines and explains a service factor as applied to the Customer’s generating unit; and

explains and justifies the assignment of a value of 75% to the service factor of the Customer’s generating unit?

(c) What mathematical equation and subsequent engineering calculation is used to derive 32,850 kWh based on the “6 hr/day” and “75% service factor” values?

(d) Since HME’s estimate of the annual energy generated by the generating unit ranges from 16,000 to 19,000 kWh, how does the Owner justify that the value of 32,850 kWh is valid?



Response:

(a) and (b)

The 6 hours per day and 75% service factors are assumptions and are not mathematically validated. These factors are only an approximation to determine whether the MG annual production is in excess of the customer’s needs and is subject to variability and interpretation. The parameters used in the calculations provide a high level indication of the MG’s production. Please refer to AUC-AE-1(3) for further reference.

(c) 32,850 kWh = 20 kW x 6 hrs/day x 365 days x 75%

(d) Please refer to HME-AE-3(a) and (b), above.







HME-AE-4


Preamble: In its Notice of Dispute, the Owner stated: “The proposed nominal generation capacity is 20 kW(…), which significantly exceeds the customer’s electrical needs since the customer’s load averages 2 kW (…) and beyond the intent to offset their onsite load…”.

Request:

(a) Since 20 kW is the generating unit’s rated direct current (“DC”) capacity to generate electrical Power, and since 2 kW is the Customer’s average annual AC electrical Power of 2 kW (as calculated from the Customer’s annual actual total alternating current (“AC”) electrical energy consumption, which has been measured and is known as 19,024 kWh), what mathematically-valid, industry-best-practice engineering documentation, calculations, practice and examples does the Owner use to independently and separately justify its reasons for comparing:

a numerical value that is a potential capacity to generate (20 kW) to a numerical value that is what was actually consumed (2 kW); and

a numerical value that is only achieved at rated environmental conditions (20 kW) to a numerical value that is an annual average under all conditions (2 kW); and

a numerical DC value (20 kW) to a numerical AC value (2 kW)?

Under what engineering principles does the Owner consider that it is valid to bring each of these comparisons to the attention of the Commission?



(b) Which performance de-rating parameters did the Owner apply to the generating unit’s solar photovoltaic array’s capacity to generate DC electrical Power (20 kW) before considering that it was valid to compare this capacity with the Customer’s average annual AC electrical Power consuming value (2 kW)? How were these de-rating parameters applied?

(c) By what means does the Owner suggest that the generating capacity parameter (20 kW) has anything at all to do with evaluating the definition of “the customer’s electricity needs” as referenced by AR27 1(1)(h)(ii)?

(d) Why did the Owner use an “oranges to apples” comparison of the DC generating unit capacity (20 kW) to the Customer’s average AC annual electrical Power consuming value (2 kW), instead an “apples to apples” comparison of the average annual AC electrical Power generating value of the generating unit with the Customer’s average annual AC electrical Power value?

(e) How does the Owner expect that the use of such radically-different system electrical Power parameters (rated DC capacity vs. average AC actual) would clarify, instead of confuse, the electrical engineering information that the Owner has submitted to the Commission and thus assist the Commission in arriving at its decision regarding AR27 1(1)(h)(ii)?

(f) What minimum and maximum range of instantaneous AC electrical Power values does the Owner expect that the Customer’s house will consume from the Owner’s electric distribution system over a year? Does the Owner’s expected maximum AC electrical Power permit the house to be properly heated?

(g) In the Owner’s comparison of 20 kW with 2 kW, what engineering data and principles validate the Owner’s choice to use the Customer’s average annual AC Power value (2 kW) instead of the Customer’s annual maximum-co-incident AC Power value? For what reasons did the Owner specifically use the Customer’s average annual AC Power value (2 kW) instead of the Customer’s annual maximum-co-incident AC Power value?

(h) What engineering data, principles and calculations did the Owner use to arrive at its suggestion that the Customer’s generating unit “significantly exceeds the customer's electrical needs” during the following periods of time:

at night;

when the solar photovoltaic array is covered in snow;

in the winter; and



during many periods when the Customer is operating their electric space heating system?

(i) What mathematically-valid industry-best-practice engineering data, principles and calculations did the Owner use to arrive at its suggestion that the size of the generating unit is “beyond the intent to offset their onsite load”?

Response:

(a) In ATCO Electric’s Response submission dated November 18, 2011, Paragraph #6 discusses the usage of a typical home and estimates the customer’s power requirements to be approx 6 kW.

ATCO Electric compared the generator’s nominal capacity with a measure of actual consumption to test the criteria listed in AR27 1(1)(h)(ii), that is whether the generator is intended to meet all or a portion of the Customer’s electricity needs.

ATCO Electric used 20 kW because the appeal by HME or behalf of the Customer specifically stated 20.9 kW as the generator’s rated capacity. The application by HME on behalf of the customer did not specify that it was expressed as a DC power rating. ATCO Electric assumes that the values entered on the application form are AC related unless otherwise stated. A DC power rating is of little value since this evaluation is based on AC assumptions.

(b) As specified in the Notice of Dispute, ATCO Electric rounded the stated generation capacity of 20.9 kW down to 20 kW, and then applied the 75% service factor and average 6 hr/day output. Given that the inverter is in full rated at only 17.2 kW, and not 20.9 kW as stated on the application, the calculated annual output in kWh will vary slightly but still be considerably greater than the annual consumption of 19,000 kW.

(c) ATCO Electric considers that the generator size bears directly on the ability of the generator to produce both demand and energy over the course of the year.

(d) At the time of the HME submitting the MG Application ATCO Electric was not made aware that the nominal capacity stated was a DC rating. Regardless of whether the value is AC or DC the electrical power requirements (demand) is a function of flow or average flow over a period of time. The MG unit capacity has a potential output of 20.9 kW, and as indicated by HME is limited by the invertors to 17.2 kW. Theoretically in a given hour the solar MG unit could export the 17 kW



less the onsite load to the distribution grid. Using the customer’s consumption data, the customer would only average 2.2 kW in a given hour (based on an annual basis) or a maximum average of 5.6 kW in the winter periods based on the peak monthly consumption during the last 12 months. The range of power requirements, depending on the time of year, could range from 0 to 6 kW. The analysis is limited by the data collected by cumulative meter installed on the customer’s residence since demand is not directly measured. Please refer to AUC-AE-1(2) for further reference.

(e) Please refer to HME-AE-4(d), above.

(f) In the absence of interval metering on the customer’s premise, there is insufficient data to determine the instantaneous minimum and maximum electrical power values. As such, the historical annual and monthly consumption billing data of the service is used to determine the customer’s electrical demand. ATCO Electric is unable to comment as to whether the house would be properly heated. Please refer to AUC-AE-1(2) for further reference.

(g) Please refer to HME-AE-4(d), above, and AUC-AE-1(2).

(h) ATCO Electric made no suggestion that the output of the unit at night or when covered with snow would exceed the Customer needs at that time. However, on a sunny day it is very likely that the generator can often produce at or near its rated power. In many instances this will coincide with a time when consumption is at or near zero, such as afternoons when there is limited or no need for lighting, cooking or heating loads.

(i) ATCO Electric serves almost 211,000 customers in 245 communities across its service area, and has been serving customers for more than 80 years. As a result, based on ATCO Electric’s professional judgment along with its review of Mr. Hildebrand’s historical usage information for the last 12 months, ATCO Electric is of the view that the customer’s power requirements to be approximately 5.6 kW. In addition, it is ATCO Electric’s experience that a 200 Amp service is a common electric panel size used in many single-family residential homes. A 200 Amp service generally requires approximately 2 kW to 4 kW of electric power. As a result, the customer’s load requirement is well below the total nominal capacity of the generating unit of 20.9 kW.







HME-AE-5


Preamble: In paragraph 6 of its Response, the Owner states: “As a result, ATCO Electric submits that the typical electric power requirements for a single-family home requiring 200 amps is approximately 2 kW to 4 kW.”

Request:

(a) What engineering data, principles and calculations is the Owner using to explain that a 200-ampere customer service panelboard will result in an AC electrical Power requirement of 2 kW to 4 kW? What value of electrical current does 4 kW of AC electrical Power represent at a customer’s 240 VAC service panelboard? By what rational engineering data, electrical principles and calculations would an electrical engineer or an electrician want to choose to install a 200 ampere-rated service panelboard instead of a 100 ampere-rated service panelboard in a typical house that has a typical AC electric Power requirement of 4 kW?

(b) For a house that has a typical AC electric Power requirement of 4 kW what typical maximum AC electrical Power values would the house’s service panelboard experience?

(c) What specifications of the Owner’s service equipment (conductor gauge, conductor metal, insulation type and service transformer rating) does the Owner typically employ in its electric distribution system to serve a site where the customer’s service equipment has a 100-ampere rating, and to serve a site where the customer’s service equipment has a 200-ampere rating?



Response:

(a) ATCO Electric submission is based on decades of experience serving similar Customers. A 200 ampere service is a common electric panel size, however it is ATCO Electric’s experience that a Customer normally does not use anywhere near the full rated capacity or even 80% of the rated capacity of the main breaker panel. In ATCO Electric’s Response submission, Paragraph #6, ATCO Electric has estimated Mr. Hildebrand’s power requirements to be approximately 6 kW based on a review of the his historical usage over the past 12 months.

4 kW of AC electric power at 120/240 volts represents 16.7 ampere if perfectly balanced between the two 120 V legs of the service. If totally unbalanced, 4 kW of AC electric power represents 33.3 ampere on one leg and the neutral.

Mr. Hildebrand’s 200 ampere service entrance panel is located outside of the house on a pole. ATCO Electric has not inspected the panel but it appears that this is a combination breaker and splitter box intended to sub feed multiple buildings or sub-panels.

200 ampere is a commonly available size for this application. Most households typically use 100 ampere sub-panel in this configuration, and there may be more than one sub-panel fed by this main service entrance panel. It is ATCO Electric’s experience that 200 ampere service entrance/splitter panels are commonly selected to accommodate the multiple sub-panels and to maintain coordination between the breaker current ratings. To clarify, a 100A breaker feeding a sub-panel such as the one that would be in the house, would typically not be fed upstream by another 100A breaker at the main service entrance/splitter. Rather, the main would usually be sized greater than the breaker feeding the sub panel.

(b) Please refer to the second paragraph of ATCO Electric’s response to HME-AE-5(a), above.

(c) For overhead services, ATCO Electric typically uses multiplexed 120/240V Aluminum service wires sized at #4, with a neutral of #6 Aluminum conductor steel reinforced, for most residences. This conductor is rated to carry approximately 90 amperes on each of the 120V legs. ATCO Electric considers the size and characteristics of the Customer’s house or facilities, information which is gathered at the time the service is built. It is not just the size of the service entrance panel that is used in selecting a size for the service conductors.



ATCO Electric’s experience is that the capacity of the #4 aluminum is usually enough for 100 or 200 ampere panels for residential customers, but that the limiting factor is the voltage drop that occurs over the length of the service conductors between the transformer and the Customer’s service entrance. Where the length of service conductor gives rise to voltage concerns, the conductor would be increased in size to reduce the overall conductor impedance between the transformer and service entrance. This voltage consideration, not capacity, is usually the determining factor that drives a decision to increase conductor size. ATCO Electric is unaware of any problems in the provision of service to Mr. Hildebrand’s site under his current loading configuration.







HME-AE-6


Preamble: In paragraph 6 of its Response, the Owner states: “ATCO Electric has estimated Mr. Hildebrand’s power requirements to be approximately 6 kW based on review of the customer’s historical usage information for the last 12 months. This estimate also recognizes that Mr. Hildebrand’s house is electrically heated as identified in paragraph 18(c) of HME’s objection letter.”

Request:

(a) How is the Owner using the phrase “power requirements” in its sentence? Does “power requirements” mean the yearly maximum electrical Power into the house? Does “power requirements” mean the maximum average hourly Power?

(b) What engineering data, principles and calculations is the Owner using to explain the statement suggesting that approximately 6 kW is the Power requirements of the Customer?

(c) What engineering data, principles and calculations would the Owner use to explain how an approximate 6 kW Power requirement would result in the Customer consuming 19,024 kWh of electrical energy per year?

(d) What engineering data, principles and calculations is the Owner using to explain that an approximate 6 kW Power requirement would cause a customer to require a 200 A electrical service panelboard instead of a 100 A panelboard?

(e) Is the Owner suggesting that 6 kW of electrical Power would permit the Customer’s house to be adequately heated?



Response:

(a) Please refer to HME-AE-1.

(b) Please refer to AUC-AE-1(2) for calculations of the Power requirements

(c) The estimated maximum average monthly demand as calculated in AUC-AE-1(2) is 5.6 kW.

(d) Please refer to HME-AE-5(a).

(e) ATCO Electric is unable to comment as to whether the house would be properly heated.







HME-AE-7


Preamble: In paragraph 6 of its Response, the Owner states: “It is important to note that since the electric heat is used in the winter months, transformer heating due to the additional loading is less of a concern.”

Request:

(a) What are the electrical, ambient air temperature and other conditions at which the Owner’s service transformer’s performance is rated? What is the numerical value of the temperature coefficient describing the rate of rise of the transformer’s operating temperature as a function of the transformer’s operating current and as a function of the ambient air temperature?

(b) Where does the Owner find the words or concepts of “transformer heating” in the text of AR27 1(1)(h)(ii)? What was Owner’s purpose of discussing the topic of transformer heating during a discussion of AR27 1(1)(h)(ii)? What is the relevance of the topic of transformer heating to the discussion regarding AR27 1(1)(h)(ii)?



Response:

(a) Transformer allowable loading is a dynamic situation which must be analyzed over a range of ambient temperatures, continuous equivalent loading, and peak loading magnitude and duration. The cumulative effects of repeated overheating of the transformer over it’s life span cause cumulative amounts of insulation degradation leading towards ultimate failure of the transformer.

ATCO Electric uses ANSI/IEEE C57.91 as specified by CSA C2.2-06, to analyze allowable loading, with the objective of maintaining the transformers within the “Normal” loss of life range.

Using ATCO Electric’s standard tables as developed from the ANSI/IEEE standard, at 30ºC with continuous equivalent loading at 90% of name plate rating, maintaining the range of ‘normal’ loss of life, a peak load of 121% of the transformer’s nameplate rating can be permitted to flow for a duration for 8 hours. If the peak load duration is limited to 4 hours, the permitted peak loading would be 136% of name plates.

ATCO Electric submits that for solar-inverter based generation systems, it is reasonable to assume 4 to 8 hours duration of peak generation will occur at times during the life span of the system. Therefore, based on ANSI/IEEE C57.91, ATCO Electric proposes that a solar-inverter generator’s nominal capacity should not exceed 130% of the transformer rating. This allows for generation at the nominal capacity at 30ºC ambient, for between 4 and 6 hours without exposing the transformer to above normal loss of life. However ATCO Electric advises caution that the maximum duration would vary considerably for other types of generators, where the nominal capacity of power could be produced for indefinite periods of time. For cases like that, the generator may not be able to exceed 100% of the nameplate rating of the transformer without increased lost of life in the transformer.

(b) The concept of transformer heating is a very basic consideration within the electric distribution and transmission industry when considering allowable transformer loading. Consideration of transformer heating is imperative to determine the appropriate size of transformers. This is discussed in paragraph #6 of ATCO Electric Response submission in discussing annual usage patterns but ATCO Electric agrees that this discussion may be more appropriate in comparing the criteria in AR27-1(1)(h)(iii) than it is to the evidence related to AR27 1(1)(h)(ii).







HME-AE-8


Preamble: In paragraph 7 of its Response, the Owner states: “Based on ATCO Electric’s review of the customer’s historical usage information, ATCO Electric is of the view that the customer’s load requirements is well below the total nominal capacity of the generating unit of 20.9 kW.”

Requests:

Where does the Owner find the text “customer’s load requirements” or the text “total nominal capacity of the generating unit” in the text of AR27 1(1)(h)(ii)? What was the Owner’s purpose in referencing this text during a discussion of AR27 1(1)(h)(ii)?

Response:

As set out in Section 1(1)(h)(ii) of Alberta Regulation 27/2008, a micro-generation generating unit means a generating unit of a customer that “is intended to meet all or a portion of the customer’s electricity needs,”. While the specific text identified by HME in the request noted above is not used in AR 27/2008, the absence is of no consequence as it is the interpretation of S. 1(1)(h)(ii) that is important. The purpose of referencing this text is to put into context the electricity needs (or the “customer’s load requirements”) of the customer relative to the generation capacity of the customer’s micro-generator.



In fact, ATCO Electric’s explanation of the customer’s load requirements is consistent with previous micro-generation determination Decisions from the AUC. In Decision 2009-044 regarding Golden Sheep Power micro-generation project application, the AUC noted the following in paragraph 14:

“In determining the electricity needs of the customer, the Commission considers two components:…”. “The Commission finds that both generation capacity of 8.6 kW and electricity generation of 75.3 MW.h exceed the customer’s needs of 4 kW and 43 MW.h.” (Underline added).

Similarly, in Decision 2009-022 regarding Golden Sheep Power micro-generation project application, the AUC noted the following in paragraph 13:

“13. After reviewing the information filed by ATCO in its submission, the Commission notes the following:

A review of the site’s historical usage information that was provided by ATCO indicates that the customer’s load averages at 3 kW. The construction of a 20 kW wind generation generating unit will greatly exceed the condition of meeting all of the customer’s electricity needs. The Micro-Generation Project does not comply with subsection 1(1)(h) (ii) of the Micro-Generation Regulation; (Underline added).

Based on the above Decisions, ATCO Electric is of the view that the term “customer’s electricity needs” or “customer’s needs” is no different than the meaning of “customer’s load requirements”.







HME-AE-9


Preamble: In paragraph 8 of its Response, the Owner states: “For the reasons outlined above, ATCO Electric does not agree with HME’s position in paragraph 8(a) of its objection letter that a customer’s electricity needs should be based on the annual electrical energy consumed.”

Requests:

(a) What specific information in paragraphs 1 to 7 of the Owner’s Response are relevant to the Owner’s position as not agreeing with HME’s position in paragraph 8(a) of its objection letter? How is the Owner using such specific information to explain its position in not agreeing with HME’s position?

(b) What engineering data, principles and calculations is the Owner using to explain its position?

Response:

(a) The reference to “the reasons outlined above” refers to Paragraphs 5 to 7 of ATCO Electric’s Response, whereby ATCO Electric has outlined and discussed HME’s non-compliance with AR 27/2008, Subsection 1(1)(h)(ii), which addresses the proposed generation capacity as significantly exceeding the customer’s electrical needs.

(b) Please refer to AUC-AE-1 and AUC-AE-2.







HME-AE-10


Preamble: In paragraph 8 of its Response, the Owner states: “Based on ATCO Electric’s estimate of Mr. Hildebrand’s demand requirements, ATCO Electric is of the view that the nominal generation capacity of 20.9 kW significantly exceeds the customer’s electrical needs, and would not comply with subsection 1(1)(h)(ii) of AR27-2008.”

Requests:

What engineering data, principles and calculations is the Owner using to explain its position?

Response:

Please refer to AUC-AE-1, AUC-AE-2, HME-AE-4(i) and HME-AE-8.







HME-AE-11

Discussion #2: Definition of micro-generator as per AR27 1(1)(h)(iii): “is, at the time of construction or installation of the generating unit, sized to the customer’s load or anticipated load or a portion of it, as evidenced by a total nominal capacity of the generating unit that does not exceed the rating of the customer’s service”

Preamble: In its Notice of Dispute, the Owner stated: “The rating of the customer’s service is only a 25 kV.A (22.5 kW) transformer with the proposed micro generation capacity significantly exceeding the rating of the transformer for the residence…”

Requests:

(a) What does the term “nominal” mean to the Owner, as used by AR27 1(1)(h)(iii)?

(b) To what specific equipment does the Owner suggest that AR27 1(1)(h)(iii) is referring when it states “customer’s service”?

HME-AE-11(b) – Revised December 15, 2011

Preamble: During a telephone call on 2011 September 20 to HME, the Owner stated that the Owner’s service transformer had a rating of 10 kV.A.

In its Response to the Objection of HME dated 2011 November 18, the Owner stated: “The proposed nominal generation capacity significantly exceeds the rating of ATCO Electric’s service transformer of 10 kV.A.”

In its letter of 2011 December 12, the Owner stated: “During the preparation of responding to the Information Requests, ATCO Electric has since conducted a further detailed field check and has



determined that ATCO Electric’s distribution service transformer that is currently installed to serve the proposed microgeneration installation is rated at 25 kV.A instead of 10 kV.A that was noted from a preliminary field check conducted at the outset of the Micro-Generator Application.”

(c) Since the Owner states that the service transformer’s apparent-Power rating is 10 kVA and that this apparent-Power rating is equal to a real-Power rating of 9 kW, thus implying a non-unity power factor for the transformer, why is the Owner not using a unity power factor to describe the real-Power rating of the Owner’s service transformer as per the accepted transformer standard CSA C2.2-06, "Pole-mounted, single-phase distribution transformers for electric utilities", Section 2.2? What engineering principles does the Owner use to justify its decision to cite 9 kW instead of as per the approved CSA standard? Why is the Owner thus informing the Commission that its 10 kVA service transformer is rated at 9 kW instead of informing the Commission that the service transformer’s real-Power rating is actually at 10 kW as per this standard?

(d) AE# 11(b) During a telephone call on 2011 September 20 to HME, the Owner stated that the Owner’s service transformer had a rating of 10 kV.A.

In its Response to the Objection of HME dated 2011 November 18, the Owner stated: “The proposed nominal generation capacity significantly exceeds the rating of ATCO Electric’s service transformer of 10 kVA.”

In its letter of 2011 December 12, the Owner stated: “During the preparation of responding to the Information Requests, ATCO Electric has since conducted a further detailed field check and has determined that ATCO Electric’s distribution service transformer that is currently installed to serve the proposed micro-generation installation is rated at 25 kVA instead of 10 kVA that was noted from a preliminary field check conducted at the outset of the Micro-Generator Application.”

What communication, documentation and preliminary field check process did the Owner use in originally identifying the Owner’s service transformer as having a 10 kV.A rating? What detailed field documentation, drawings and records is the Owner able to provide that shows whether a service transformer with a rating of 10 kV.A has ever fed the Customer’s site?

(e) What communication, documentation and detailed field check process did the Owner use to identify the presently-installed service transformer as having a 25 kV.A rating? What detailed field documentation, drawings and records is the



Owner able to provide that shows that the presently-installed service transformer has a rating of 25 kV.A? What documentation is the Owner able to provide to show when the Owner’s service transformer was changed to one with a 25 kV.A rating?

Response:

(a) ATCO Electric considers the term nominal to mean the rating as found on the name plate of the equipment.

(b) ATCO Electric considers the “customer’s service” to include ATCO Electric’s transformer and low voltage conductors from the transformer to the service entrance, as well as the Customer’s service entrance equipment. For larger generators this could extend in to the primary distribution facilities required to provide service to the facility.

(c) CSA C2.2 Sec. 2.2 defines kVa rating as the output, assumed to be at the rated voltage and unity power factor, on which specified maximum values of loss, regulation and temperature rise are based. This narrow definition is used to calculate those quantities and to express some of the quantities in a per-unit or percent basis, based on the rated kVa.

The Standard goes on to state, in section 4.3-1 that ANSI/IEEE C57.91 is specified to be used to determine the transformer’s loading capabilities. In applying this ANSI/IEEE standard, the actual loading is kVa compared to the name plate kVa. It is therefore important for ATCO Electric to estimate the actual kVa that will flow through the transformer, which in its’ experience is rarely at unity power factor. It is inappropriate to evaluate this transformer’s loading capability at the theoretical unity power factor that is defined in the standard for the narrow purpose of calculating and forming a basis for the per-unit or percent impedance, power and energy losses, voltage regulation and temperature rise.

(d) The request to verify the transformer size was made from the Key Accounts group to the field engineering office in Slave Lake based on the information provided by HME. Based on the customer’s premise address/name and ATCO Electric’s mapping information, the customer’s premise was incorrectly associated to a 10 kVa transformer in the same geographic area instead of the 25 kVa transformer. The field engineering office indicated the customer was served from a 10 kVa transformer. ATCO Electric does not believe, nor have record of, the service for this address being a 10 kVa transformer.



(e) On Dec. 6, 2011, in order to confirm service conductor sizes and distances a detailed field check was done. This was the first indication that the original information was incorrect. ATCO electric cannot produce documentation regarding this date and reason for any transformer changes in the past at this site.

Please refer to attached photos and map contained below within this document, as well as the hand-drawn field check sketch attached as file HME-AE-11(e) Attachment 1.pdf

HME-AE-11(e) Attachment 1







HME-AE-12


Preamble: In paragraph 11 of its Response, the Owner states: “ATCO Electric does not agree with HME’s assertion in paragraph 8(b) of its objection letter that the rating of the utility’s equipment should not influence whether the customer’s micro-generation project complies with subsection 1(1)(h)(iii) of AR27/2008.”

Requests:

What engineering data, principles and calculations is the Owner using to explain its position? Response:

It is ATCO Electric’s view that the rating of the utility’s equipment should directly influence whether the customer’s micro-generation project complies with subsection 1(1)(h)(iii) of AR27/2008. This view is based on generally accepted and Commission approved cost causation principles. As noted in paragraph 14 of ATCO Electric’s Response submission, ATCO Electric must size its assets prudently to ensure that it does not overbuild its distribution system. This is analogous to understanding why residential roads entering into a subdivision development are not built based on all homeowners driving into the area all at the same time on a daily basis. If that were the case, the infrastructure required including the size of residential roads would be more significant. This imprudent design approach would result in significant upward pressure on customer rates as they would be responsible to share in the associated incurred costs, and may also result in the customer’s direct contribution to the cost of their dedicated service being significantly higher for the over-building.







HME-AE-13


Preamble: In paragraph 12 of its Response, the Owner states: “ATCO Electric notes that in AR27/2008, Subsection 1(1)(h)(iii), the nominal capacity of the generating unit must be sized to the customer’s load.”

Requests:

What nominal capacity of solar photovoltaic generating unit would be required, with the same solar photovoltaic array angle configuration as the Customer’s, in order for the Customer’s generating unit to be considered as “sized to the Customer’s load”?

Response:

The criteria laid out in AR27 1(1)(h)(iii) specify that the nominal capacity of the generation unit does not exceed the rating of the customer’s service “as evidenced by a total nominal capacity of the generating unit that does not exceed the rating of the customer’s service.”

Please refer to AUC-AE-2(3)(b) for an analysis of the capacity of the service conductors to manage the voltage drop associated with the 17.2 kW generator. Further, note that ATCO Electric has recommended in AUC-AE-2(5) that the voltage rise in the service conductors as a result of generation at the nominal capacity be limited to three percent of the nominal service voltage.



The following calculations will give the maximum allowable nominal capacity for the generator at this location:

3% x 120V = 3.6V;

3.6V ÷ 0.11Ω = 32.7A

32.7A x 240V = is 7854 Watts, or 7.85KW

Thus ATCO Electric submits that a generator with a nominal capacity of 7.85 kW would meet the proposed criteria,







HME-AE-14


Preamble:

Requests:

(a) What is the Customer’s load requirement in the winter? How does the Customer’s load requirement in the winter compare with the sizing of the generating unit and with the amount of electrical energy generated by the generating unit in the winter?

(b) How does the Customer’s annual load requirement compare with the generating unit’s annual total generated electrical energy or with the generating unit’s annual average generated electrical Power?

(c) What size of generating capacity from a solar photovoltaic generating unit operating in the winter, with the same solar photovoltaic array angle configuration as the Customer’s, would satisfy the Customer’s load requirement in the winter?



Response:

(a) Please refer to HME-AE-4(d) for winter load requirement. The generating nominal capacity of 20.9 kW and maximum AC export of 17.3 kW is larger than the load requirements. ATCO Electric does not have sufficient information to compare to the amount of electrical energy generated by the generating unit in the winter.

(b) Please refer to HME-AE-4(d).

(c) Please refer to HME-AE-13.







HME-AE-15


Preamble:

Requests:

How does “customer’s service panel” relate to HME’s position in paragraph 8(b) of HME’s Letter of Objection? Regarding HME’s Letter of Objection, how does HME’s explanation in paragraphs 17(b) and 17(c) relate to HME’s position as stated in paragraph 8(b)?

Response:

In paragraph 8(b) of the HME’s Letter of Objection, HME appears to be requesting clarification from the AUC regarding the intention of the “rating of the customer’s service” as set out in AR27 1(1)(h)(iii). It is ATCO Electric’s view that the rating of the customer’s service is not the panel size in the customer’s home or building, but rather ATCO Electric’s service transformer and associated conductors from the service transformer to the customer’s premise. ATCO Electric does not agree with HME that the utility shall size its service requirements to feed the house based on the limit imposed by the rating of the panel breaker. As noted in HME-AE-12, this imprudent design approach would result in an excessive over-built distribution system that would be inefficient and costly. Please also refer to HME-AE-5(a) for a discussion on service panel size.







HME-AE-16


Preamble:

Requests:

(a) How does the Owner define the term “rating” as it applies to a 200 ampere current rating of a customer’s service panelboard? How does the Owner’s explain the meaning of “rating” in AR27 1(1)(h)(iii) as it refers to rating of a customer’s service panelboard?

(b) What specific text in HME’s submissions is the Owner using to support its suggestion that HME or anyone else is assuming that a customer will “require” 48 kW of Power based on a 200-ampere rating of a customer’s service panelboard?

Response:


(b) ATCO Electric is referring to paragraph 17(b), of HME’s Objection Letter whereby it states that “These current ratings of the Customer’s service provide for a maximum capacity for consuming electrical power and a maximum capacity for



generating electrical power of 48 kW (or 38 kW) at a nominal AC electrical voltage of 240 V.”. This statement appears to suggest that since the panel is able to accommodate up to 48 kW of load, the customer is able at any time to increase its electrical requirements up to a maximum of 48 kW with the implied understanding that the upstream distribution utility facilities are adequate to serve the additional load. The point that ATCO Electric is disputing in paragraph 13 of its Response is to explain that it is inappropriate for HME to assert that a simple mathematical concept can be used to determine what the maximum capacity for consuming electrical power is for the existing service.







HME-AE-17

Discussion #3: The Owner’s statement: “ATCO Electric would need to upgrade the customer’s service to accommodate the proposed generation.”

Preamble: In its Notice of Dispute, the Owner stated: “ATCO Electric would need to upgrade the customer’s service to accommodate the proposed generation.”

Requests:

(a) What are the environmental and electrical conditions under which the Owner’s service transformer is rated? What Canadian standard defines these transformer rating conditions?

(b) What is the overcapacity rating of the Owner’s service transformer? What are the electrical and environmental conditions under which the overcapacity rating of the Owner’s service transformer is given?

(c) Under electrical overcapacity conditions what happens to the service transformer’s operating characteristics (such as voltage and operating temperature)? What is the long-term effect on the transformer of such electrical conditions? How does the Owner respond to situations where it finds its transformers operating under such conditions?

(d) Does the Owner permit its service transformers to operate at significant amounts of overcapacity for 4 to 8 hour periods? What is the Owner’s standard practice if it determined that its service transformers were operating at significant amounts of overcapacity? How often has the Owner found such transformer overcapacity conditions on its electric distribution system?



Response:

(a) Please refer to ATCO Electric’s response to HME-AE-7(a).

ATCO Electric purchases all single phase, single bushing, pole mounted distribution transformers 10 kVa to 167 kVa in size to comply with the latest edition of CSA C2.2, Pole Mounted, single-phase distribution transformers for electric utilities. That standard references ANSI/IEEE C57.91 to address allowable loading, and so ATCO Electric follows that standard to establish practices and standards for allowable transformer loading.

(b) Please refer to ATCO Electric’s response to HME-AE-7(a).

(c) Please refer to ATCO Electric’s response to HME-AE-7(a) for discussion of temperature and loading.

With respect to voltage, a transformer will see a voltage drop at the transformer bushings that is directly proportional to load in percent of the nameplate rating and the impedance of the transformer, as expressed in a percent (%IZ) on the transformer nameplate. Typically, for a 25 kVa transformer, for full load the voltage drop at the secondary bushings will be approximately 1.5%.

(d) Please refer to ATCO Electric’s response to HME-AE-7(a). ATCO Electric routinely finds transformers approaching overcapacity conditions and schedules the transformers for upgrade to a larger size.







HME-AE-18

Discussion #4: Power quality

Preamble:

Requests:

(a) What amount of surplus electrical energy from this generating unit would be expected to cause voltage rise issues? What amount of surplus electrical Power from this generating unit would be expected to cause voltage rise issues?

(b) What engineering data and calculations show the environmental and electric distribution system operating conditions under which any expected voltage rise issues would occur, including the magnitude of the expected voltage rise, and its severity, duration and consequences? What range of solutions does the Owner normally consider in mitigating such voltage rise issues?

(c) What role do automatic tap changers play the ability of the Owner to adequately manage voltage rise as well as voltage drop considerations? Does the Owner use automatic tap changers in its service transformers in order to adequately manage voltage rises as well as voltage drops?

(d) How would the magnitude of the implied voltage rise compare with the magnitude of the voltage drop that is experienced due to the Customer’s present maximum AC electrical Power consumption?

(e) Are any low-voltage conditions already existing on the Owner’s electric distribution system near to the Customer such that the Owner could appreciate the benefit to its electric distribution system arising from the Customer’s generating unit in providing voltage support to the Customer’s neighbours?



Response:


(b) Please refer to AUC-AE-2(3) and AUC-AE-2(4).

(c) Automatic tap changers are not a prudent solution at the customer utilization and not commonly used at 120/240 voltage levels. ATCO Electric employs automatic tap changers in voltage regulators at primary distribution voltages of 7.2 kV and above, to regulate the voltage on the primary distribution system; and the cost of these voltage regulators is prohibitive for use at utilization voltages. Voltage regulators can cost in the neighborhood of $20,000 and require frequent maintenance, which is not prudent for a small group of customers when a better basic solution is available such as conductor upgrades or the addition of a span of primary wire and a transformer closer to the customer’s premise. Any voltage regulation at the 25 kVa system would be ineffective in mitigation of voltage concerns on the service wires.

(d) Please refer to AUC-AE-2(1) and AUC-AE-2(3).

(e) ATCO Electric is unaware of any low voltage conditions near to the customer. A solar generator is at any rate unsuitable as a means of mitigation for low voltages because the solar generator cannot be counted upon to mitigate low voltage situations during periods of low or non-production by the generator (e.g. night time, cloudy days, or days when the panels are covered with snow.) Further, ATCO Electric does not consider it likely that owners will be interested in undertaking the risk of liability for mis-operation of their equipment in times of need. Low voltage concerns are better mitigated in more basic ways such as reducing the impedance of the service conductors by increasing their size or reducing their length.







HME-AE-19

Discussion #5: Customer-supplied load information

Preamble: In its Notice of Dispute, the Owner stated: “The customer has not indicated, nor demonstrated, that their on-site load will be increasing in the future.”

Requests:

(a) In what way did the Owner indicate to HME that the information provided by HME was inadequate? What information did the Owner ask HME to provide so as to assist the Owner in gaining an understanding of the Customer’s future site plans and any resulting change in energy consumption? What opportunity did the Owner provide to HME to supply such information and clarification that the Owner would need? Did the Owner communicate such requests to HME in writing at all? If so, what evidence is the Owner able to provide of such written communication?

(b) Who is the Owner’s contact person for HME to contact regarding this micro-generator application? Did the Owner provide HME with this person’s contact information during the 15-day period between HME’s submission of its Micro-Generator Notice of Application (September 19) and the issuance of the Owner’s Notice of Dispute to HME (October 05) (“Application Period”)? If so, on what date did the Owner provide this information and by what method of communication? If not, why not? Did this person make any contact with HME during the Application Period?

(c) Did Daryl Pattison, supervisor of the Owner’s Key Account representatives, return any of HME’s telephone messages during the Application Period? If so, what were the dates and nature of the returned calls? If not, why not?



Response:

(a) ATCO Electric received the MG application of the generating unit as submitted by HME. In the statement quoted in the Preamble from the Notice of Dispute ATCO Electric is not intending to imply an inadequate application by HME. During conversations with HME regarding the proposed MG installation, there simply was not any indication from HME that the load requirements of the customer’s facility were changing or increasing which effectively establishes that the annual energy consumption as indicated on the application form is valid and the customer’s premise would likely have a similar consumption pattern in future years. The statement is only an observation; ATCO Electric submits that the onus is on HME to provide any supplemental information relevant to the application.

(b) HME and ATCO Electric were in discussions during the 14 day period between the received application date of September 21, 2011 and the Notice of Dispute submitted to the AUC on October 4, 2011. This included a Senior Account Representative and the Manager of ATCO Electric’s Key Accounts. Prior to HME submitting its MG Application HME was in several discussions with one of ATCO Electric Senior Account Representatives as well.

(c) This is not relevant to the proceeding and eligibility of the MG application.







HME-AE-20

Discussion #5: Customer-supplied load information

Preamble: In its Response, the Owner states: “ATCO Electric staff was in discussion with HME before September 19, 2011, regarding the eligibility of its proposed micro-generation application.”

Requests:

What were the approximate dates and nature of this discussion? At any time did the Owner’s staff courteously remind HME of the previous discussion or provide any opportunity to recollect such a discussion? If not, why not? If so, how did HME respond?

Response:

The conversations were with one of ATCO Electric’s Senior Account Representatives prior to HME submitting its MG Application, and based on preliminary information provided by HME the general nature of the conversations were around the eligibility of the proposed MG and ATCO Electric’s facilities. Due to the general discussion and inquiry, the conversations were not recorded or monitored.

ATCO ELECTRIC Micro-Generation Determination Application ... PROCEEDING 1477 -- ATCO... · Howell...

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